Which sentence contains an inappropriate shift in tense? a. the barrier will drop down every time that a train approaches the crossing. b. as i came in the front door, eddie is going out the back door. c. if anyone knows the answer, she does.

B.   the sentence should read:   as i came in the front door, eddie went out the back door(or something similar to that)

a. this is a correct change in tense.   "the barrier will drop down every time that a train approaches the crossing."   basically this says that "when the train does this, the barrier does "

b. this is incorrect because the sentence starts in the past progressive tense, but ends in the present progressive.

c.   this is also correct.

A. will drop --> will have dropped
b. is going --> was going